Variable delivery fan



Dec. 19, 1967 sv OLDBERG VARIABLE DELIVERY FAN 2 Sheets-Sheet 1 Original Filed Oct. 22, 1965 INVENTOR.

OLDBERG SIDNEY FIG.2

ATTORNEYS V Dec. 19, 1967 s. OLDBERG VARIABLE DELIVERY FAN 2 Sheets-Sheet 2 Original Filed Oct. 22, 1965 FIG.5

INVENTOR.

I SIDNEY BY ATTORNEYS United States Patent C) 3,358,773 VARIABLE DELIVERY FAN Sidney Oldberg, Birmingham, Mich., assignor to Eaton Yale & Towne Inc., a corporation of Ohio Continuation of application Ser. No. 501,469, Oct. 22, 1965. This application June 6, 1966, Ser. No. 555,616 19 Claims. (Cl. 170160.11)

This application is a continuation of application Ser. No. 501,469, filed Oct. 22, 1965, now abandoned.

This invention relates in general to a variable delivery fan, and more particularly to a variable delivery fan having fan blades mounted on a support member so as to be capable of movement relative to the support member between first and second positions at which the blades move different amounts of air.

A variable delivery fan is particularly useful when applied to automotive vehicles for engine cooling purposes. Fans in automotive vehicles are associated with the radiator and are generally driven by the engine and rotate at speeds which are proportional to the engine speed. When such a vehicle is operated at high speeds, the air through which the vehicle passes and commonly referred to as ram air, strikes the front of the vehicle. This ram air at high speeds is sufficient to provide the requisite amount of cooling without substantial aid of a fan. When the vehicle is operated at low speeds, the fan is relied on to cool the engine since the amount of ram air providing a cooling effect is slight. Since the fan is driven from the engine at a high vehicle speed fan speed is correspondingly high and the angular speed of the fan blade tips is extremely high. This high tip speed causes considerable noise which is objectionable.

According y, an important object of the present invention is the provision of a new and improved fan for use in an automotive vehicle for engine cooling purposes and which delivers the requisite amount of air for cooling purposes at both high and low vehicle speeds and at an extremely low noise level.

Another object of the present invention is the provision of a fan, as noted in the next preceding object, wherein fan noise at high engine speeds is controlled by movement of the fan blades from a radially extended first position wherein the blades have a high tip speed and at which the fan delivers a maximum amount of air at a particular speed to a second position of substantially smaller radial extent with a lower tip speed and at-which the fan produces a minimurn'flow of air at the particular speed and wherein the blades remain in their second position above the particular speed so that the noise produced and air flow are reduced from that which would be produced if the bladeshad not moved.

A further object of the present invention is the provision of a new and improved fan having fan blades pivotally supported'for movement relative to a rotatable support member between positions of maximum and minimum delivery at any given speed and which are biased by a spring means to the position relative to the support member at which the fan delivers a maximum amount of air and wherein the fan blades move against the bias of the spring means to their positions of minimum delivery at a particular speed.

A still further object of the present invention is the provision of a new and improved fan having fan blades pivotally supported for movement relative to a rotatable support member between positions of maximum and minimum delivery and which are biased by a spring means to a first position relative to the support member at which the fan delivers a maximum amount of air and wherein the fan blades move against the bias of the spring means to their position of minimum delivery at a particular speed, and wherein the pivotal movement of the blades is effected due to the aerodynamic forces acting on the blades in oppositition to the bias of the spring, which forces at the particular speed exceed the force applied to the blades by the spring and thereby effect pivoting movement of the blades.

Other objects and advantages of the present invention will be apparent from the following descripition of a preferred embodiment thereof made with reference to the accompanying drawings forming a portion of this specification and wherein:

FIG. 1 is an elevational view of a fan present invention;

FIG. 2 is a fragmentary View of a portion of the fan shown in FIG. 1;

FIG. 3 is a fragmentary sectional mately along line 3-3 of FIG. 1;

FIG. 4 is a fragmentary view of a modified fan embodying the present invention; and

FIG. 5 is a fragmentary sectional view taken approximately at line 55 of FIG. 4.

The present invention provides an improved fan having fan blades which are supported for movement between two positions. One position of the fan blades provides a maximum amount of air flow at a given speed while at the other position the air flow produced is lower than what it would be had the blades not been moved. However at the other position fan noise is greatly reduced. Such a fan is particularly useful in an automotive vehicle and reduces fan noise at high vehicle speeds when high air flow produced by the fan is not essential due to the ram air. As representing the preferred embodiment of the present invention, a fan A for use in an automotive vehicle is illustrated in FIG. 1.

The fan A comprises a rotatable support member 2 mounted on a shaft 1 for rotation therewith and fan blades 7 connected to support member 2 so as to be rotatable with the support member-and movable with respect thereto. The support member 2 includes a hub portion 3 fixedly secured to the shaft 1 and having an axially extending cylindrical bore 4 therethrough adapted to receive shaft 1. A plurality of arms 5 extend radially from h-ub, 3 at spaced intervals on the circumference of the hub. Each arm 5 carries a fan blade 7 thereon located near the outer radial end thereof. The fan blades 7 on rotation produce a flow of air dependent upon the disposition of the fan blades and speed of rotation thereof.

As noted-above, each fan blade 7 is movable relative embodying the view taken approxitosupport arm 5. Each fan blade 7 specifically is capable of pivoting about an axis transverse to the fan blade between a position in which the longitudinal axis of the fan blade is generally radially directed, as shown in dotted lines in FIG. 2, and a position where the longitudinal axis of the fan blade is generally tangentially directed as shown in full lines in FIG. 2. When the fan blades are in a position where their longitudinal axes are generally radially directed as shown in dotted lines in FIGS. 1 and 2, the air through which the blades pass, upon rotation in the direction indicated by the arrows in FIGS. 1 and 2, is acted upon by front and back surfaces 15 and 16, respectively, on the blades in a well known manner to produce a flow of air axially of the fan and in the direction of the arrow in FIG. 3. In this position the fan blades produce a maximum flow of air for a given tudinal axes so that the flow producing interaction between the air and surfaces 16 is at a minimum for a particular fan speed. Moreover, since the radial extent of the blade is small in this position, the tip velocity of the blade is minimized accordingly, and the fan blades in this position produce a minimum amount of noise for a given fan speed.

The fan blades 7 and their mode of connection to arms 5 for movement relative thereto are identical and therefore only one fan blade will be described with its mode of connection to its associated arm. Each fan blade 7 has generally concentrically curved side edges 11 and 12 extending in a general direction of the longitudinal axis of blade 7 and joined by end edges 13 and 14 forming generally lobular end portions. Fan blade 7 is curved in a direction generally transverse to its longitudinal axis as shown in FIG. 3 and has front and rear curved surfaces 15 and 16, respectively. Front surface 15 has an indent 8 extending generally along the longitudinal axis thereof which indent is formed by walls 9 and 10. Indent 8 has a hole 17 located in side wall 10 thereof which hole forms a part of the means for mounting the blade to the support member and is located at or near the center of gravity of the fan blade. The location of hole 17 governs the length of the indent 8 which, as illustrated, extends slightly more than half of the length of the fan blade. When a fan blade 7 is in its radially extended position, the associated arm 5 is nested in the indent 8.

Each fan blade 7 is supported, as noted above, for pivotal movement relative to its associated arm 5. Each blade 7 is pivoted about the axis of a pin which extends through aligned openings 6 and 17 in the fan blade 7 and arm 5. Each pin 20 is held in the openings by a conventional nut and washer arrangement shown generally at 2.3 and is fixed to the arm through which it ext ends by a set screw 24 which extends through the arm 5 and engages the pin in such a manner as to prevent rotation of the pin 20 relative to the arm 5. Each blade 7 is biased to its position of maximum delivery 'by a suitable spring means. In the present embodiment, a spirally wound spring 18 biases its associated blade to its dotted position shown in FIG. 2. The spirally wound spring 18 is coiled about the pin 20 and has one end held in a slot 21 at the end of pin 20 by a snap ring 22 and the other end projects through an opening 19 in side Wall 9 of indent 8. The end projecting through the opening 19 has a flange 18a thereon which engages the fan blade and biases the fan blade toward its radially outwardly extended position shown in dotted lines in FIG. 2. The side wall 9 of the indent 8 functions as a stop to limit movement of the blade 7 by the spring 18.

When the fan is stopped, or is rotating at low speeds, the springs 18 hold the blades in their radially extended position. As the rotational speed of the fan increases, aerodynamic forces build up on the surface 16 of the blades 11, which forces are greater at the radially outermost tip of the blade than at the radially innermost portions. As rotational speed increases, these forces increase to the point Where the biasing force of each of the springs 18 is overcome and the blades rotate in a counterclockwise direction, as viewed in FIG. 1, about pin 20 to a position of minimum radial extent. For purposes of explanation, it should be clear that aerodynamic forces acting outwardly of pivot pin 20 are proportionately greater than aerodynamic forces acting inwardly of the pivot pin at a given fan speed due to the difference in distance between these portions of the fan blades and the center of rotation of the fan. Of course, the pivoting moment produced by the aerodynamic forces exerted on the fan blade outwardly of the pivot pin will be opposed by a moment produced by the forces exerted on the blades inwardly of the pivot pin. However, since the aerodynamic forces acting on the blades outwardly of the pivot pin are greater than the forces acting inwardly of the pivot pin, a differential pivot moment will exist when the fan is rotated. This differential pivot moment may be considered to be the force which overcomes the bias of spring 18 as described above. The pivoting movement of the blades stops when the aerodynamic force acting on the blades is balanced by the biasing force of the springs 18. The counterclockwise rotation of the fan blades of course causes tension in the springs 18 to be increased and when the rotational speeds of the fan are decreased springs 18 will cause clockwise rotation of the fan blades and return the blades to their radially extended position.

The operation of the fan A should be clear from the description above. When the fan is stopped or rotating at speeds less than a predetermined speed in a clockwise direction as viewed in the drawings, blades 7 are in their radially extended position. Under these conditions the springs 18 hold the fan blades so that the support arms are engaged with side walls 9 of the indents.

As the speed of fan rotation increases, aerodynamic forces build up on each blade such that at a predetermined speed, the spring tension will be balanced by the aerodynamic forces acting on the fan blade. This speed may be determined by tensioning the spring as desired and due to the construction of the fan blades 7. At speeds in excess of this predetermined speed, aerodynamic forces overcome the spring force and rotate the blade in a counterclockwise direction so as to shorten the radial extent of the blade. This rotation of the blade reduces air flow delivered by the fan but also reduces the noise produced by the fan. As the fan speed of rotation decreases, the spring force will overcome the aerodynamic forces and cause a clockwise rotation of the fan blade. This clockwise rotation will continue until the fan blade has reached its maximum radial extent previously described. When the blades are in their radially extended position, the air through which the blade is passed crosses the blades transversely to the curvature of the blades, previously discussed, and is propelled axially of the fan blade due to the interaction between it and the curved portion in a well known manner. When the blades are in their position of minimum radial extent, they form a generally circular band about the support member which may be termed a toroid. The air through which each fan blade passes, crosses the blade in a direction generally parallel to its curvature and tangent to the circular band formed by the blades, so that the interaction between the blade and the air is substantially reduced, resulting in a small delivery of air by the fan. This small delivery of air by the fan is accompanied by a reduced tip velocity of the fan blade since each blade tip has been moved radially inwardly, and as a consequence the noise created by the fan under such conditions is extremely small in comparison to that produced by conventional fans operated under the same conditions.

FIGS. 4 and 5 illustrate a modified fan B embodying the present invention. The fan B is driven in a counter clockwise direction as viewed from the vehicle engine, not shown, by a shaft 40. The fan includes a support member 41, which is drivingly connected to the shaft 40 by bolts 42 which extend through a collar member 4912 carried by the shaft. The fan B includes fan blades 43 which are pivotally mounted on the support member 41 so that the blades 43 are rotatable with the support member but pivotally movable with respect thereto about an axis normal to the plane of rotation of the support member.

The support member 41 is a one-piece, dish-like memher and includes a rearwardly extending wall 44 and a radially extending flange 45. The flange 45 includes a plurality of arms 46 upon which fan blades 43 are mounted.

The fan blades 43 and their connection with the support member 41 are identical in construction and therefore only one fan blade will be described with its connection with the support member. Fan blade 43 is formed from a thin sheet of material, preferably a light metal, and inciudes a body portion 47 and a blade portion 50. Blade portion 50 is of such configuration that when it is moved through the air, as described, a flow of air is produced in a manner well known to those skilled in the art. Body portion 47 is preferably formed by a double thickness of the sheet material and includes an enlarged end portion 51 which is of such size and shape that the center of gravity of the fan blade 43 is located in the body portion and between blade portion 50 and end portion 51. A hole 52 is formed in the body portion of the fan blade at the center of gravity of the blade. The hole 52 is aligned with a hole 53 in the arm 46 of the support member and a pivot pin 54 projects therethrough. Pivot pin 54 includes a body portion 55 having a cap portion 56 at one end thereof in engagement with the body portion 47 of the fan blade. Body portion 47 is connected to the arm 46 and fixed against rotation with respect thereto. The cap portion 56 of the pivot pin overlies a portion of the body portion 47 of the fan blade and prevents axial movement of the fan blade relative to the support member. As shown in FIG. 4, the fan blade 43 pivots with respect to the support member between a first radiaHy extended position, shown in full lines, and a second radially retracted position, shown in phantom lines. The blade 43 is biased toward its first position and by a spring 57 encircling the pivot pin 54 and having an end 60 thereof in engagement with the body portion of the fan blade and an opposite end 61 in engagement with a pin member 62 extending through the pivot pin 54. The blade 43 is prevented from moving beyond the aforementioned first position by a stop means 58 located on the body portion 47 which engages arm 46.

As the fan is driven in a counterclockwise direction at low velocities each fan blade is held in a radially extended position and provides cooling air for the vehicle engine. As engine and vehicle speeds increase, aerodynamic forces build up along a leading edge 63 of the blade portion 50 of the fan blade and tend to move the fan blade from its first radially extended position towards its second, radially retracted position against the bias of the spring 57.

At a predetermined speed of rotation of fan B the aerodynamic forces acting on the fan blade will overcome the bias spring 57 and move the fan blade toward its second position. Of course, when the fan blades are in their second position, the radial extent of the blade is less than that of the first position such that the tip velocity of the blade at a given speed of rotation will be less when the blades are in their second position than when the blades are in their first position and the noise produced by these blades will be correspondingly reduced. Fan blade 43 is prevented from rotating with respect to the support member past its second position by contact between the end 60 of the spring 57 and the flange 45 of the support member.

When the speed of rotation of the fan B decreases the aerodynamic forces acting on the blades will decrease correspondingly and the fan blades will be moved from their second toward their first position by the action of spring 57 as it overcomes the aerodynamic force exerted on the blade.

While but two forms of the invention have been shown and described, it is to be understood that other forms, modifications and adaptations could be made and it is intended to cover all such forms, modifications and adaptations falling within the scope of the claims which follow.

I claim:

1. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and movable with respect thereto from a first radially extended position wherein said blades provide a first fluid flow to a second radially retracted position wherein said blades provide a second fluid flow less than said first fluid flow at a given speed of rotation of said support member, and means for disposing each of said fan blades in their said first position at rotational speeds less than a predetermined rotational speed and providing for movement of said blades to their said second position at rotational speeds in excess of said predetermined speed.

2. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and movable with respect thereto at a predetermined speed of rotation between a first radially extended position and a second radially retracted position, each of said fan blades when in their first position having a surface portion acted upon by aerodynamic forces during rotation tending to resist rotation of the fan blade and efiective at a predetermined speed of rotation to move said fan blade relative to said support to its second position, and means for moving each of said fan blades from said second to said first position at speeds less than said predetermined rotational speed and allowing said blades to remain in said second position at rotational speeds in excess of said predetermined speed.

3. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and pivotal with respect thereto between a first radially extended position wherein said blades provide a first fluid flow and a second radially retracted position wherein said fan blades provide a second fluid flow smaller than said first fluid flow at a given speed .of rotation of said support member, pivot means supporting each of said fan blades for pivotal movement from their said first to their said second positions, and means for pivoting said blades from said second position to said first position and holding said blades in said first position at rotational speeds less than said predetermined speed.

4. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and pivotal with respect thereto between a first radially extended position wherein said blades provide a first fluid flow and a second radially retracted position wherein said fan blades provide a second fluid flow smaller than said first fluid flow at a given speed of rotation of said support member, pivot means supporting each of said fan blades for pivotal movement from their said first to their said second positions, and means for pivoting said blades from said second position to said first position and holding said blades in said first position at rotational speeds less than a predetermined speed, each of said fan blades having a surface portion acted upon by aerodynamic forces during rotation and which forces tend to resist rotation of the fan blade with said support and are eflective at said predetermined speed of rotation to move said fan blade relative to said support to its second position.

5. The fan mechanism of claim 4 wherein the radial distance from the axis of rotation of said support member to the radially outermost portion of said fan blades decreases as said fan blades are moved from said first to said second positions.

6. The fan mechanism of claim 4 wherein said means for pivoting said blades includes biasing means urging said fan blades toward said first position.

7. The fan mechanism of claim 4 wherein said pivot means includes a pin means supporting each of said blades for pivotal movement with respect to said support member and a helical spring surrounding said pin means and having a portion engaged with said fan blades and a portion engaged with said pin means.

8. The fan mechanism of claim 4 wherein each of said fan blades have surfaces which in the second position of said fan blades form a substantially continuous toroid about said axis.

9. The fan mechanism of claim 4 wherein the fan blades include a first blade portion having a relatively large area and upon which substantially all of said aerodynamic forces act and a second weighted portion substantially smaller in area than said first portion and heavier than said first portion, said first and second portions extending oppositely from said pivot means.

10. A fan mechanism as defined in claim 4 wherein the fan blades include a first blade portion having a relatively large area and radial extent when in said first position, and a second weighted portion having a radial extent substantially smaller than the radial extent of said first portion, and in which said pivot means supports said fan blades for pivoting about the center of gravity of said fan blades.

11. The fan mechanism of claim 4 wherein said pivot means supports said fan blades for pivoting movement about the center of gravity of said fan blades.

12. The fan mechanism of claim 4 wherein said pivot means includes a separate pin member supporting each of said blades for pivotal movement about an axis located at the center of gravity of said fan blades and said means for pivoting includes a spirally wound spring having one end engaging a portion of the fan blade and the other end engaging said pivot pin.

13. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and each blade movable with respect thereto between a first radially extended position wherein said blade produces a first fluid flow and a second radially retracted position wherein said fan blade produces a second fluid flow of smaller volume than said first flow at a given speed of rotation of said support member, said blades having an outer portion located a first radial distance from said axis when said blades are in their first position and an outer tip portion located at a second radial distance smaller than said first distance when said blades are in their second position, means supporting each of said fan blades on said support member for pivotal movement about the center of gravity of said fan blade between said first and second positions in response to aerodynamic forces acting thereon at a predetermined rotational speed, spring means urging each of said fan blades toward said first position and operable to move said blades from said second position toward said first position at rotational speeds less than said predeter mined speed, and said support having a plurality of portions each of which is engageable with a portion of one of said fan blades to limit movement of said blades by said spring means and which portions are in engagement when said blades are in their first position.

14. The fan mechanism of claim 13 wherein said spring means is a helical spring having an end engaged with said fan blade and another end engaged with a member of said supporting means.

15. A fan mechanism as defined in claim 13 wherein said support includes a plurality of arm portions each supporting a fan blade, each of said fan blades including an indent portion defined by a pair of side walls in which said arm portion is received, and a side wall of said blade being biased into engagement with said arm portion by said spring means.

16. A fan mechanism as defined in claim 15 wherein said spring means is a spirally wound spring with one end thereof extending through a side wall of said indent.

17. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and pivotal with respect thereto between a first radially extended position wherein said blades provide a first fluid flow and a second radially retracted position wherein said fan blades provide a second fluid flow smaller than said first fiuid flow at a given speed of rotation of said support member, pivot means supporting each fan blade for pivotal movement between its said positions about another axis substantially parallel to said axis of rotation of said support member, said another axis of each fan blade being located at substantially the center of gravity of each respective blade.

18. A fan mechanism comprising a support member rotatable about an axis, a plurality of fan blades mounted on said support member for rotation therewith and pivotal with respect thereto between a first radially extended position wherein said blades provide a first fluid how and a second radially retracted positon wherein said fan blades provide a second fluid flow smaller than said first fiuid flow at a given speed of rotation of said support member, pivot means supporting each fan blade for pivotal movement from its first to its second position about another axis substantially parallel to the axis of rotation of said support, and said fan blades having surface portion which in total define a substantially continuous toroid extending about said axis of rotation of said support when said blades are in their said second positions.

19. A fan mechanism as defined in claim 18 wherein said another axis of each fan blade is located at substantially the center of gravity of said respective fan blade.

References Cited UNITED STATES PATENTS 2,134,660 10/ 1938 Everts. 2,282,436 5/ 1942 Taylor 170-16052 2,601,495 6/1952 Bell ll60.ll 2,885,012 5/1959 Heintzelman 160. 11 2,992,686 7/ 1961 Heintzelman et al. l70160.ll 3,077,229 2/ i963 Heintzelman l70l60.11

' EVERETTE A. POWELL, JR., Primary Examiner. 

17. A FAN MECHANISM COMPRISING A SUPPORT MEMBER ROTATABLE ABOUT AN AXIS, A PLURALITY OF FAN BLADES MOUNTED ON SAID SUPPORT MEMBER FOR ROTATION THEREWITH AND PIVOTAL WITH RESPECT THERETO BETWEEN A FIRST RADIALLY EXTENDED POSITION WHEREIN SAID BLADES PROVIDE A FIRST FLUID FLOW AND A SECOND RADIALLY RETRACTED POSITION WHEREIN SAID FAN BLADES PROVIDE A SECOND FLUID FLOW ANNULAR THAN SAID FIRST FLUID FLOW AT A GIVEN SPEED OF ROTATION OF SAID SUPPORT MEMBER, PIVOT MEANS SUPPORTNG EACH FAN BLADE FOR PIVOTAL MOVEMENT BETWEN ITS SAID POSITIONS ABOUT ANOTHER AXIS SUBSTANTIALLY PARALLEL TO SAID AXIS OF ROTATION OF SAID SUPPORT MEMBER, SAID ANOTHER AXIS OF EACH FAN BLADE BEING LOCATED AT SUBSTANTIALLY THE CENTER OF GRAVITY OF EACH RESPECTIVE BLADE. 